They were not, for one thing, indigenous to this world but came from a much heavier planet nearer galactic center.

Very little different really from the other natives of this heavy planet.

Life of a kind that never visited a heavy planet's surface.

Small and heavy inner planets swam deliberately in their short orbits around the sun.

And a heavy planet will always have an atmosphere for braking.

It's a very heavy planet, loaded with uranium and stuff from bismuth on out.

Humans are a smaller people, better adapted to this somewhat heavier planet than we are.

Those muscles had been developed on a heavy planet.

Also, observation has ruled out planets heavier than 0.7 Jupiter mass with a period of one year or less.

There was no science in it, just his greater strength from exercise and existence on a heavier planet.